parity, n. The state or condition of being equal in any respect.
disparity, n. The quality or state of being of unequal rank, condition, circumstances, etc.; inequality or dissimilarity in respect of age, amount, number, or quality; want of parity or equality.
(from the Oxford English Dictionary Online)
health disparities Syn: health inequalities, health gap. The difference between the levels of health indicators that are observed in a defined population group and the level that would be expected if this group had the health experience of the segment of the population that ranks highest in health indicators.
(from Dictionary of Public Health, via Oxford Reference Online)